Update error block css

app/assets/stylesheets/pages/diff.scss

@@ -162,7 +162,8 @@
     }
     .diff-loading-error-block {
-      padding: $gl-padding $gl-padding*2;
+      padding: $gl-padding * 2 $gl-padding;
+      text-align: center;
     }
   }

app/assets/stylesheets/pages/merge_requests.scss

@@ -770,13 +770,11 @@
 .btn-link-retry {
   &[disabled] {
     cursor: not-allowed;
-    filter: alpha(opacity=65);
-    -webkit-box-shadow: none;
     box-shadow: none;
     opacity: .65;
     &:hover {
-      color: #777;
+      color: $file-mode-changed;
       text-decoration: none;
     }
   }